Hybrid electric vehicles may use an engine and electric machine for propulsion. The electric machine can be powered by a high voltage (e.g., 300 volt) battery. The electric machine and high voltage battery can be electrically connected via a high voltage bus. Typically, the high voltage battery and associated bus are connected through a main contactor. Prior to closing the main contactor, the high voltage bus may be at a voltage less than the high voltage battery. As such, the high voltage bus may be pre-charged by connecting it to the high voltage battery through, for example, a pre-charge contactor and resistor to increase the voltage on the high voltage bus. After the high voltage bus is pre-charged, the main contactor can be closed to directly connect the high voltage battery to the high voltage bus.